The present invention is directed to an improved apparatus and process for effecting glow discharge. More specifically, the present invention is directed to an apparatus and process for uniformly generating a flow of ions between a glow bar electrode and one or more electroconductive substrates. One embodiment of the present invention is directed to an apparatus for effecting glow discharge comprising an elongated electrically conductive glow bar electrode, means for applying a potential to the glow bar electrode, thereby generating ions, means for creating a flow of ions from the glow bar electrode to a second electrode, and a shield situated to block partially the flow of ions between the glow bar electrode and the second electrode, said shield having a plurality of apertures through which ions can flow between the glow bar electrode and the second electrode, each aperture having associated therewith at least one shutter, said shutters being capable of at least partially blocking the flow of ions through the apertures, each shutter individually movable to a plurality of positions to adjust the flow of ions through the apertures. Another embodiment of the present invention is directed to a vacuum coating apparatus comprising (a) a vacuum chamber, (b) means for evacuating the vacuum chamber, (c) means for introducing gas into the vacuum chamber, (d) at least one mandrel member inside the vacuum chamber, upon which can be situated a plurality of electrically conductive substrates, and (e) at least one glow discharge apparatus comprising an elongated electrically conductive glow bar electrode, means for applying a potential to the glow bar electrode, thereby generating ions, means for creating a flow of ions from the glow bar electrode to the electrically conductive substrates, and a shield situated to block partially the flow of ions between the glow bar electrode and the electrically conductive substrates, said shield having a plurality of apertures through which ions can flow between the glow bar electrode and the electrically conductive substrates, each aperture having associated therewith at least one shutter, said shutters being capable of at least partially blocking the flow of ions through the apertures, each shutter individually movable to a plurality of positions to adjust the flow of ions through the apertures, wherein the number of apertures in each shield is equal to the number of substrates situated upon each mandrel. Yet another embodiment of the present invention is directed to a process for providing uniform ion bombardment of a plurality of electrically conductive substrates by a single glow discharge apparatus which comprises (a) providing a vacuum coating apparatus comprising (1) a vacuum chamber, (2) means for evacuating the vacuum chamber, (3) means for introducing gas into the vacuum chamber, (4) at least one mandrel member inside the vacuum chamber, upon each of which are situated a plurality of electrically conductive substrates, (5) means for measuring the temperature of each electrically conductive substrate on each mandrel, and (6) at least one glow discharge apparatus comprising an elongated electrically conductive glow bar electrode, means for applying a potential to the glow bar electrode, thereby generating ions, means for creating a flow of ions from the glow bar electrode to the electrically conductive substrates, and a shield situated to block partially the flow of ions generated between the glow bar electrode and the electrically conductive substrates, said shield having a plurality of apertures through which ions can flow between the glow bar electrode and the electrically conductive substrates, each aperture having associated therewith at least one shutter, said shutters being capable of at least partially blocking the flow of ions through the apertures, each shutter individually movable to a plurality of positions to adjust the flow of ions through the apertures, wherein the number of apertures in each shield is equal to the number of substrates situated upon each mandrel; (b) generating a partial vacuum within the vacuum chamber; (c) generating a flow of ions between the glow bar electrode and the electrically conductive substrates, thereby raising the temperatures of the electrically conductive substrates, (d) subsequent to step (c), measuring the temperatures of the electrically conductive substrates, (e) adjusting the positions of the shutters so that the flow of ions between the glow bar electrode and substrates having a temperature lower than a desired temperature is increased, (f) adjusting the positions of the shutters so that the flow of ions between the glow bar electrode and substrates having a surface temperature higher than a desired temperature is limited, and (g) repeating steps (c), (d), (e), and (f) until a desired degree of uniformity is achieved with respect to the temperatures of the electrically conductive substrates.
The use of glow discharge techniques is known in the fabrication of photoconductive imaging members. For example, U.S. Pat. No. 4,019,902 (Leder et al.), the disclosure of which is totally incorporated herein by reference, disclosed a photoreceptor having improved flexibility comprising a metal- or metal-coated flexible substrate and an inorganic photoconductor layer in charge blocking contact, the photoreceptor being obtained by initially bombarding the metal substrate, as cathode, with positive ions of an inert gas of low ionization potential under glow discharge in the presence of oxygen, and exposing the resulting oxidecoated substrate to a vapor cloud of photoconductor material consisting essentially of charged and uncharged material in an electrical field, utilizing the metal substrate as a cathode and a donor of said vapor cloud of photoconductor material or container thereof as an anode, the latter step being effected in combination with at least part of the initial bombardment step.
In addition, U.S. Pat. No. 3,914,126 (Pinsler), the disclosure of which is totally incorporated herein by reference, discloses a process for applying a photoconductive layer to a flexible nickel or nickel-coated substrate by initially subjecting a nickel sheet or belt to an acid etching bath followed by anodizing treatment in an electrolytic bath to obtain at least two intermediate metal oxide layers such as nickel oxide layers having superior adhesive and charge-injection-blocking characteristics. In addition, this references discloses that in addition to or as an alternative to the electrolyte treatment, a nickel oxide layer can be laid on the substrate by glow discharge techniques, wherein the nickel substrate is made the anode under partial vacuum with a current density of about 3.times.10.sup.-5 A/cm.sup.2 and a voltage (cathode) of about 2.5. kV for a period of about 1 to 5 minutes.
U.S. Pat. No. 3,907,650 (Pinsler), the disclosure of which is totally incorporated herein by reference, discloses a process for applying a photoconductive layer to a flexible nickel or nickel-coated substrate by initially subjecting a nickel sheet or belt to an acid etching bath followed by anodizing treatment in an electrolytic bath to obtain at least two intermediate metal oxide layers such as nickel oxide layers having superior adhesive and charge-injection-blocking characteristics. In addition, this references discloses that in addition to or as an alternative to the electrolyte treatment, a nickel oxide layer can be laid on the substrate by glow discharge techniques, wherein the nickel substrate is made the anode under partial vacuum with a current density of about 3.times.10.sup.-5 A/cm.sup.2 and a voltage (cathode) of about 2.5. kV for a period of about 1 to 5 minutes.
U.S. Pat. No. 4,959,287 (Pai et al.), the disclosure of which is totally incorporated herein by reference, discloses a xeroradiographic imaging member containing a substrate having an electrically conductive surface, an electroradiographic insulating layer selected from the group consisting of selenium and selenium alloys, and an overcoating layer containing nigrosine, a charge transport compound and a specific copolyester resin. The substrate, which is electrically conductive and of a material such as aluminum, titanium, nickel, chromium, brass, copper, zinc, silver, tin, or the like, can be cleaned and oxidized by glow discharge treatment of the substrate in a vacuum coater, wherein formation of the oxide layer can be closely monitored and controlled by regulation of the coater bleed gas flow rate with a precision flow gauge and valve, with pressure maintained between about 10 and about 100 micrometers of mercury, substrate temperature maintained at less than about 115.degree. C. (240.degree. F.), and flow rate sufficient to maintain a high oxygen content atmosphere (about 21 percent for air).
U.S. Pat. No. 4,770,965 (Fender et al.), the disclosure of which is totally incorporated herein by reference, discloses an electrophotographic imaging member comprising a conductive substrate, an alloy layer comprising selenium doped with arsenic having a thickness of between about 100 micrometers and about 400 micrometers, the alloy layer comprising between about 0.3 percent and about 2 percent by weight arsenic at the surface of the alloy layer facing away from the conductive substrate and comprising crystalline selenium having a thickness of from about 0.01 micrometer to about 1 micrometer contiguous to the conductive substrate, and a thin protective overcoating layer on the alloy layer, the overcoating layer having a thickness between about 0.05 micrometer and about 0.3 micrometer and comprising from about 0.5 percent to about 3 percent by weight nigrosine. The photoreceptor is prepared by providing a conductive substrate, cleaning the substrate, heating an alloy comprising selenium and from about 0.05 percent to about 2 percent by weight arsenic until from about 2 percent to about 90 percent by weight of the selenium in the alloy is crystallized, vacuum depositing the alloy on the substrate to form a vitreous photoconductive insulating layer having a thickness of between about 100 micrometers and about 400 micrometers containing between about 0.3 percent and about 2 percent by weight arsenic at the surface of the photoconductive insulating layer facing away from the conductive substrate, applying thin protective overcoating layer on the photoconductive insulating layer, the overcoating layer having a thickness between about 0.05 micrometer and about 0.3 micrometer and comprising from about 0.5 percent to about 3 percent by weight nigrosine, and heating the photoconductive insulating layer until only the selenium in the layer adjacent the substrate crystallizes to form a continuous substantially uniform crystalline layer having a thickness up to about one micrometer. The conductive substrate can be oxidized by exposure to glow discharge treatment in the vacuum coater, wherein formation of the oxide layer can be closely monitored and controlled by regulation of the coater bleed gas flow rate with a precision flow gauge and valve, with pressure maintained between about 10 and about 100 micrometers of mercury, substrate temperature maintained at less than about 115.degree. C. (240.degree. F.), and flow rate sufficient to maintain a high oxygen content atmosphere (about 21 percent for air).
U.S. Pat. No. 4,557,993 (Matyjakowski), the disclosure of which is totally incorporated herein by reference, discloses a process for preparing an electrophotographic imaging member comprising providing a nickel substrate, heating the nickel substrate to a temperature of at least 260.degree. C. in the presence of oxygen until a continuous layer of nickel oxide forms on the substrate, and depositing at least one photoconductive insulating layer on the continuous layer of nickel oxide. This patent also discloses the treatment of nickel substrates by glow discharge prior to deposition of a photoconductive layer thereon.
U.S. Pat. No. 4,310,614 (Connell et al.), the disclosure of which is totally incorporated herein by reference, discloses a process for deposition of continuous pin-hole free tellurium films with thickness to less than 150A on a suitable substrate by first pretreating the substrate prior to film deposition. Ion sputtering or bombardment of the substrate surface with an inert gas prior to tellurium evaporation creates a dense coverage of nucleation sites on the substrate, which improves the adhesiveness and resistance to abrasion and oxidation of the deposited film while providing very thin pinhole free films of uniform thickness and desired crystallite orientation.
U.S. Pat. No. 4,099,969 (Leder), the disclosure of which is totally incorporated herein by reference, discloses a photoreceptor having improved flexibility and durability comprising a metal- or metal-coated substrate and an inorganic photoconductor layer in charge blocking contact with the substrate, the photoreceptor being obtained by initially bombarding a grounded or floating substrate with electrons and non-metallic high energy ions in the presence of oxygen and exposing the resulting clean oxide-coated substrate to a vapor cloud of photoconductor material bombarded by electrons and non-metallic ions to form high energy ions, the vapor cloud being initially obtained by evaporation from a crucible in a coated under glow discharge conditions; the latter functional step being optionally effected in combination with at least part of the initial bombardment step.
U.S. Pat. No. 4,072,518 (Leder), the disclosure of which is totally incorporated herein by reference, discloses a one-step process, method and corresponding xerographic photoreceptor obtained thereby, having all or part of the hole generating layer in the trigonal form, the process being effected and the photoreceptor obtained through the use of a glow discharge and ionizable inert gas. If desired, the substrate can be cleaned and provided with a charge blocking layer by initial bombardment of the substrate as a cathode with positive ions of an inert non-metallic gas in a vacuum coater.
U.S. Pat. No. 3,845,739 (Erhart et al.), U.S. Pat. No. 3,861,353 (Erhart et al.), and U.S. Pat. No. 3,911,162 (Erhart et al.), the disclosures of each of which are totally incorporated herein by reference, discloses a method and apparatus for vapor depositing a thin film of material on image retention surface substrate bodies comprising the steps of positioning a plurality of substrate bodies on a plurality of elongated, horizontally extending support mandrels, rotating each of the mandrels about an associated longitudinal axis thereof while simultaneously transporting the plurality of mandrels in an annular path about a horizontal axis, establishing an evacuated atmosphere about the assembly of mandrels, and vaporizing a material which is positioned in a planar array of crucibles located within a path defined by the annular travel of the mandrels. In a specific embodiment, the substrate bodies are preheated by a plurality of glow bar assemblies. In addition to heating the rotating substrate bodies to the desired temperatures for the deposition of the photoconductor material, the glow bar assemblies in the case of certain substrate body materials, such as aluminum, establish an interface surface on the substrate support bodies. The establishment of this interface at a time immediately prior to the deposition of the photoconductor in an evacuated atmosphere results in an enhanced photoconductor characteristic over that provided by means wherein the interface is formed in an ancillary apparatus and then subjected to an additional time interval and handling under atmospheric conditions.
U.S. Pat. No. 4,152,747 (Fisher), the disclosure of which is totally incorporated herein by reference, discloses an electrode which has at least one internal channel and an adjustable gate or slot to permit passage of gaseous material to be ionized from the internal channel and then in proximity to one or more outside faces of the electrode in a suitable area of electron emission, the electrode being placed in an electrical field in convenient proximity to an electrode or body of opposite charge. The apparatus is suitable for preparing electrophotographic photoconductors.
The use of glow discharge techniques is also disclosed in U.S. Pat. No. 3,914,126, U.S. Pat. No. 3,907,650, and in Ignatov, J. Chimie Physique, 54, pages 96 et seq. (1957), the disclosures of each of which are totally incorporated herein by reference.
While known apparatus and processes for treating photoreceptor substrates by glow discharge techniques are suitable for their intended purposes, a need remains for improved methods and apparatus for treating conductive imaging member substrates for the purposes of heating and/or cleaning, and, in some instances, for the purpose of oxidizing the substrate surface. In addition, there is a need for improved methods and apparatus for treating conductive materials such as plates, drums, belts, or the like by glow discharge. Further, a need remains for a method and apparatus for treating a plurality of substrates by glow discharge so that each substrate so treated is uniformly exposed to ion bombardment. Additionally, there is a need for a method and apparatus for treating a plurality of substrates by glow discharge wherein it is possible to control and vary the amount of glow plasma to which each substrate is exposed. By controlling the amount of glow plasma to which each substrate is exposed, the temperature variation between substrates can be controlled tightly, which enables efficient photoreceptor fabrication by vacuum evaporation techniques.